Apparatus and method for drying materials



Oct. 4, 1960 Filed April 13, 1955 D. S. BAKER APPARATUS AND METHOD FORDRYING MATERIALS 11 Sheets-Sheet 1 I INVENTOR. fia/yul mr ATTORNEYS Oct.4, 1960 D. s. BAKER 2,954,613

APPARATUS AND METHOD FOR DRYING MATERIALS Filed April 13, 1955 11Sheets-Sheet 2 INVENTOR.

Da/vt'd glad/ en BY ATTORNEYS Oct. 4, 1960 D. s. BAKER APPARATUS ANDMETHOD FOR DRYING MATERIALS ll Sheets-Sheet 3 INVENTOR. DMS,Bc/ken BYFiled April 15, 1955 ATTORNEYS Oct. 4, 1960 D. s. BAKER I 9 2,954,613

APPARATUS AND METHOD FOR DRYING MATERIALS Filed April 13, 1955 llShets-Sheet 4 INVENTOR. Dad r21 5, Bake/ A T TORNEYS Oct. 4, 1960 D. s.BAKER APPARATUS AND METHOD FOR DRYING MATERIALS Filed April 13, 1955 v11 Sheets-Sheet 5 n a e 9I| NM 5 9 /2 /4 x T M/ (W f? W 8 k 5 5/ 0U a 5!mm w g p N m m L I/ O HV f. m 2 9 I 5/ 7 a m 8 a no 5 w. fr Mw Ho 9 m 5i 7 0 O 7 8 I -H R N 7 4. a 7 a I J I n W Ts W I '8 w WJ 2 I I/ 8 9 w 66 O 5 ATTORNEYS Filed April 13, 1955 Oct. 4, 1960 D. s. BAKER 2,954,613

APPARATUS AND METHOD FOR DRYING MATERIALS 1]. Sheets-Sheet 6 figi I"INVENTOR.

Da/L'v'c/ $360521 LBY E 1 W E A TTORNEYS Oct. 4, 1960 D. s. BAKERAPPARATUS AND METHOD FOR DRYING MATERIALS Filed April 13, 1955 llSheets-Sheet 7 IN V EN TOR. S eaker A T QfSN- IIIIH lllllllllillll l IH] Oct. 4, 1960 D. s. BAKER 2,954,613

APPARATUS AND METHOD FORDRYING MATERIALS Filed April 1a, 1955 11Sheets-Sheet a /54 m a n /29 W=- igr l I B2 I I, U fig Z I IN V EN TOR.DW/ 5, Err/Yer ATTORNEYS Oc 1960 D. s. BAKER 2,954,613

APPARATUS AND METHOD FOR DRYING MATERIALS Filed April 13, 1955 llSheets-Sheet 9 is 13 37241 I INVENTOR. Dan/ (1 S, 80/76! A TTORNEYS lOct. 4, 1960 D. s BAKER APPARATUS AND METHOD FOR DRYING MATERIALS p m ue 1 HI- augh? m K N w. r..\......k..fi.k,nl' T a m m n w m s A w .l h sW U a W D Y 8 NW\ NW\ w? ..M

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United States Patent APPARATUS AND METHOD FOR DRYING MATERIALS David S.Baker, 475' th Ave., New York 17, NY.

Filed Apr. 13, 1955, Ser. No. 501,087

28 Claims. (Cl. 34-102) This invention relates to apparatus for dryingvarious materials by the removal of volatile fluid therefrom. Generallythe fluid which is removed by the drying is water and its removal isaccelerated by heat. However, this in- ,vention is applicable to theremoval of other volatile foodstuffs.

The main object of this invention is to provide improvement in apparatusand method for drying, driving off or otherwise removing fluid frommaterials of the kinds exemplified hereinabove. It is a further objectof this invention to overcome difficulties and drawbacks which have beenincident to the provision of economical and efiicient apparatus andmethods for drying wet materials,

the term drying being applied generally to the driving off or otherremoval of a volatile fluid with the recovery of a non-volatile residuein either a dry or partially dry condition. When reference is madeherein to a material being wet, the volatile liquid or fluid may eitherbe water, which is commonly the case, or some other substance orsubstances which may be removed in the form of a vapor.

Certain objects and features of this invention relate to the provisionof improved apparatus for drying materials of the kinds referred to andexemplified hereinabove in which there is a rotary drum having a heatedoutside surface surrounded in part by an endless conveyor belt meansadapted to retain, compress or sandwich material being dried between itand the outside surface of the drum, the apparatus including improvedand simplified means for repeatedly removing materialbeing dried fromthe outside surface of the drum and refeeding it between the drumsurface and the endless conveyor belt means.

In connection with the foregoing objects and features of this invention,other objects and features relate more particularly to apparatus whereinthe inside surface of the endless conveyor belt means and the outsidematerialreceiving surface of the drum cooperate to form a feed throatthrough which material being dried must enter in being compressed orsandwiched between the inside surface of the belt and the outsidesurface of the drum, means being employed which provides improvedcontrol and better feeding action as the material enters and Theimproved feeding means which constitutes a feature of this invention isapplicable to the formation into a layer of unformed workable materialsuch as a mass of wet material to be dried, as by feeding the materialbetween traveling surfaces ice posed adjacent relation at which theworkable material becomes formed into a layer. Furthermore, specificobjects and features of this invention relate to the provision incontiguous relation to one of the traveling surfaces providing the feedthroat of what is referred to here'- in and in the claims as curtainmeans that provides a restriction plate for contacting unformed workablematerial during its ingress into the feed throat and providingdiminished but effective tractive contact. with the material enteringthe feed throat. Still further objects and features of this inventionrelate .to the provision of such curtain means in the form of fingerssuch as spaced flexible strips which extend into the feed throat andpreferably are contiguous with or drag against the outside surface ofthe drum when the feed throat is provided by and between the outsidesurface of a drum and an endless conveyor belt means which approachesthe outside surface of the drum generally tangentially so as to providea material-feeding portion in addition to a portion concentricallysurrounding a portion of the outside surface of the drum.

Other objects and features of this invention relate to the provision ofimproved apparatus for drying materials whereby more effective andsimplified means may be utilized for causing the material to becomesandwiched between the outside heated surface of a rotatable drum andendless conveyor belt means concentrically surrounding a portion of saiddrum and Worked axially along the drum while being repeatedly removed.from the drum for contact with an atmosphere into which vapor may escapeand being refed through feed throat means constituted by the outsidesurface of said drum and the inside surface of the endless conveyor beltmeans. Further objects and features of this invention relate to theimprovements that are afforded by the combination of the means forproviding such axial movement of the material during the aforesaidoperations of being repeatedly removed from the drum and refed so as tobe carried thereby with the improved means hereinabove referred to forcontrolling and making more effective for attaining the desired dryingthe tractive action of the converging traveling surfaces at the feedthroat where the inside surface of the endless conveyor belt meansapproaches the outside surface of the drum.

Other objects and features of this invention relate to the improvementof drying apparatus of the type comprising a rotary drying drumsurrounded in part by an endless conveyor belt means by the provision ofmeans whereby material may be first cam'ed on the surface of the drumand then removed therefrom in a space where the material may becomeexposed to an atmosphere for receiving vapor separated from the materialbeing dried. More particularly, such objects and features of thisinvention include the disposition and actuation of the endless conveyormeans so as to form a loop at one side of the drum, thereby providing anaeration space adjacent that portion of the drum surface within the loopof the endless conveyor belt means. Within the loop so formed means maybe provided for removing material from the drum surface and causing itto fall in the aeration space and become redeposited on the insidesurface of the endless conveyor belt means for being refed between theoutside surface of the drum and the inside surface of the endlessconveyor belt means. Preferably the curved ex- *tremity of the loop isso supported as to provide upper in the form of a feed throat thatbrings them into opand lower reaches of the endless conveyor belt meansand thereby provide an aeration space of substantial size. Both the drumsurface and the endless conveyor belt means are normally imperforate andby thus providing a loop of the character aforesaid an aeration chamberis provided which utilizes the upper and lower reaches of the endlessconveyor belt means and part of the outside surface of the heated drum.Moreover, in such case a material after removal from the outside surfaceof the drum for aeration in the space within the loop may fall directlyon the inside surface of the lower portion of the loop and any materialwhich may adhere to the upper portion of the loop and fall therefrombecomes refed without loss for repeated compression so as to besandwiched between the outside surface of the drum and the insidesurface of the endless conveyor belt means so as to be carried on oneside of the drum over the top of the drum for entry into the top of thespace within the loop.

Further objects and features of certain embodiments of this inventionrelate to the provision of wall means within the space provided bydisposing the endless conveyor belt 'means' in the form of a loop at oneside of the .-;rotatably mounted drying drum. Preferably the wall .meansincludes both a dividing partition wh1ch 1s normal to the drum axis anda confining partition spaced from the outside surface of the drying drumwhereby .improved removal of vapor-laden atmosphere from the .spacewithin the loop is provided. However, either or both of such wall orpartition means may be omitted.

Other features of this invention relate more generally to means forproviding a zone wherein material to be dried is exposed to atmospherefor escape of vapor and for removal of vapor-laden atmosphere therefrom.

Other features ofthis invention relate to improved means for inducingaxial travel of material to be dried ;while it is being repeatedlyremoved from the surface of ;a drying drum and refed so as to becomesandwiched be- -tween the outside surface of the drying drum and theinside surface of endless conveyor belt means that concenjtricallysurrounds a portion of the outside surface of the drum.

In connection with such means, improved seal means is provided accordingto this invention between the inside surface of the endless conveyorbelt .means and the outside surface of the rotatably mounted -dru.madjacent one or both ends of the drum.

Improved seal means is also provided according to this in- Such sealadjacent the other end of the drum for receiving and directing thewholly or partially dried material so that it .will not be refed ontothe surface of the drum while .maintaining uniformity of the compactedlayer at all times notwithstanding shrinkage due to loss of fluid fromthe mass being dried. Preferred seal means which conzstitute a furtherfeature of certain embodiments of this invention utilizes a successionof pieces of flexible resilient material attached to one member so thatthe ex- .tremities thereof remain in resiliently maintained con-.tacting relationship with another member. means may be provided betweenthe endless conveyor belt means and either a confining side wall or thecircum- Such seal ferential periphery of the drum at one or both ends.For providing a seal for a drum or other circular member I and anotherconcentric member the seal means preferably is so made that theresilient flexible pieces are overlapping in side-by-side relationshipas, for example, by using a plurality of overlapping leaf springs ofstainless steel or the like which extend laterally so as to provide aresiliently deformable ring adapted to be maintained in resil- .1entcontacting relation with an opposed arcuate surfac for maintaining aseal.

Another object and feature of this invention resides in the provision ofapparatus of the type and for the purpose set forth which includes arotary drum having a .peripheral surface surrounded in part by anendless con- :veyor belt means in which there is improved means forsealing one end of the drum and the endless Conveyor '15- 4 belt meansand means for cleaning impacted material from the seal means.

Other objects and features of this invention relate to improvedutilization of a drying drum so that an effective drying surface isprovided both by the outside surface and by the inside surface of thedrum. More particularly, such objects and features of this inventionpreferably provide means whereby material being dried is repeatedlycascaded in an aerating atmosphere while being dried on the outside ofthe drum but is maintained in sliding contact with the inside surface ofthe drum with minimum of agitation or tumbling, such apparatus beingespecially suitable for carrying out the final drying of a product withminimum of difficulty resulting from excessive dusting. Other objectsand features of certain embodiments of this invention relate toimprovements in temperature control as between the outside and insidesurfaces of the drying drum.

Other objects and features of certain embodiments of this inventionrelate to the provision of drying apparatus comprising a drum having amaterial-receiving outside surface and improved means for heating thedrum. More particular objects and features of such embodiments of thisinvention relate to the locating of zones of combustion with referenceto the drum and to the provision of a combustion Zone or chamberprovided at least in part by the inside surface of the drum and toimproved means for directing and utilizing the products of combustion.

vOther objects and features of this invention relate to improved methodsfor drying materials of the kinds referred to and exemplifiedhereinabove and to the provision of improved apparatus for carrying outthe im proved methods of the invention.

Preferably the features and improvementsof this invention are employedin combination so as to obtain the most effective and efiicient mannerof practicing this invention. However, the features and improvements ofthis invention may be employed in apparatus wherein they may be employedseparately or in coacting relation not involving all of the features ofthe preferred combinations that are shown and described herein.Moreover, other objects, features and advantages of this invention willappear from the following description in connection with theaccompanying drawings which, for purposes of exemplification, showtypical embodiments of this invention and illustrate the practicethereof.

In theaccompanying drawings:

Fig. 1 is a view in elevation of one side of a drier apparatus includingfeatures of the invention, the drive mechanism for the-primary feeder ofthe apparatus being omitted;

Fig. 2 is a view in elevation, with parts broken away, of the right handside of the apparatus seen in Fig. 1;

Fig. 3 is a diagrammatic view in section of the upper portion of theapparatus seen in Figs. 1 and 2,-the view being taken generally on line3-3 of Fig. 2, and, for the sake of clarity, omitting certain framemembers and the primary feeder mechanism of the apparatus;

Fig. 4 is a partial plan view, partly in section, taken on the line 4-4of Fig. 3;

Fig. 5 is a view in plan showing portions of the endlessbelt conveyor,the rotary drum and a seal means on one end of the drum for sealing orclosing a materialreceiving space between the belt and the drum;

Fig; 6 is a view taken on the line 66 of Fig. 5

i and looking at the left side of the structure seen in Fig. 5;

Fig. 7 is a view in section, the section being taken on the line 7-7 ofFig. 5;

Fig. 8 is a fragmentary. perspective sectional showing .of certain ofthe parts appearing in Figs. 5, 6 and 7;

Fig. 9 is a view in section through certain elements of the sealstructure seen in Fig. 7;

Fig. 10 is a more or less diagrammatic side view in elevation on alarger scale of a portion of the apparatus seen in Fig. 1, the viewshowing particularly one end of the rotary drum of the apparatus andmechanism associated with it;

Fig. 11 is a more or less diagrammatic view in elevation taken on line11-411 of Fig. with parts broken away or in section;

Fig. 12 is a view on a larger scale of some of the elements seen in Fig.11;

Fig. 13 is an elevational view on line 13-13 of Fig. 12 with some partsin section;

Fig. 14 is a view somewhat similar to Fig. 1 2 but showing a modifiedform of material feeder structure for feeding material between the drumand endless conveyor belt;

Fig. 15 is a view somewhat similar to Fig. 13 but showing the modifiedform of material feeder structure seen in Fig. 14;

Fig. 16 is a diagrammatic view in section of a modified form of theapparatus seen in Figs. 1 and 2;

Fig. 17 is a diagrammatic view in plan of a portion of the apparatusseen in Fig. 16;

Fig. 18 is a diagrammatic view in section, the section being taken online 1818 of Fig. 16;

Fig. 19 is a diagrammatic sectional, elevational view of a modified formof drying cylinder or drum and asso ciated apparatus which may besubstituted for the drying cylinder or drum in the drier shown in Figs.1, 2 and 3, or the drying cylinder and drum shown in Figs. 16, 17 and18;

Fig. 20 is an end view in elevation, with parts broken away, of theapparatus seen in Fig. 19;

Fig. 21 is a detail section taken on the line 21-41 of Fig. 20;

Fig. 22 is a diagrammatic view, partly in section and partly inelevation, of another modified form of cylinder or drum and heatingmeans therefor, which may be substituted for the drier or cylinder ordrum in the drier seen in Figs. 1, 2 and 3 or the drier cylinder anddrum shown in Fig. 16 of the drawings;

'Fig. 23 is a view in section, the section being taken on line 23-23 ofFig. 22;

Fig. 24 is a view in section, the section being taken on line 24-24 ofFig. 22;

Fig. 25 is a view, partly in section and partly in elevation, showingmeans for preventing axial movement of the cylinder or drum seen inFigs. 22 through 24;

Fig. 26 is a diagrammatic view illustrating the mechanism for rotatingthe cylinder or drum seen in Figs. 22 through 25 and also the cylinderor drum seen in Figs. 27 through 29;

Fig. 27 is a diagrammatic view, partly in section and partly inelevation, of another modified form of cylinder and heating meanstherefor, which may be substituted in the drier seen in Figs. 1, 2 and3;

Fig. 28 is a diagrammatic view in section, the section being taken online 2823 of Fig. 27; and

Fig. 29 is a diagrammatic side view in section, the section being on theline 29-29 of Fig. 27.

The drier apparatus shown in Figs. 1 through 4 of the drawings includesan open generally rectangular main frame 30 formed of suitable uprightand cross angle members welded together. Within the frame 3%) there is ahollow material-heating cylinder or drum 31 adapted to be heated bysteam or hot water. Drum 31 includes two axially aligned stub shafts 32,one at each of its opposite ends, by which it is mounted for rotationabout a generally horizontally disposed laterally extending axis throughbearings 33 on horizontal members of the frame 30 and adjacent one ofits upright ends.

Steam or hot water is introduced into the cylinder or drum 31 through aconduit formed by one of the stub shafts 32 which is hollow and throughwhich water or condensate may be exhausted from the drum through aconduit or pipe that extends to adjacent the bottom of the insidesurface of the cylinder or drum.

6 Adjacent the opposite upright end of main frame 30 there is agenerally horizontally extending shaft 34 carried for rotation insuitable bearings 35 mounted on the frame 30. The axis of shaft 34 isparallel with and spaced forwardly of the axis of rotation of cylinderor drum 31 and the two lie on substantially the same horizontal plane.This shaft 34 carries a pair of spaced sprocket wheels 36 that carry anddrive an endless conveyor belt 37 looped around and extending betweenthe spaced cylindrical drum 31 and the sprocket wheels 36. Endlessconveyor belt 37 is fully described hereinafter, but it is pointed outhere that it includes two endless chains 38, one at each side, thatcooperate with the sprocket wheels 36 and rims on the ends of the drum31.

Shaft 34, and consequently the sprocket wheels 36, conveyor belt 37 andcylinder or drum 31 are driven in a counter-clockwise direction, asviewed in Figs. 1 and 3 of the drawings, by an electric motor 39 througha speed reducer 30, a sprocket 41, chain 42 and a sprocket 43 on shaft34.

A portion of the endless conveyor belt 37 is concentrically disposedabout one side of the cylinder or drum 31 and another portion is loopedoutwardly from the opposite side to form an aeration chamber, pocket orspace 44 in which material being dried is subjected to aeration. In theembodiment shown the curved extremity of the loop portion of the endlessconveyor belt means is supported by the sprocket wheels 36 and theaeration chamber, pocket or space 44 is defined at its bottom by thebottom run or reach 45 of the conveyor belt 37, at one end by theexposed or uncovered side of the cylinder or drum 31, on the top by thetop run or reach 46 of conveyor belt 37, and at the end opposite thedrum 31 by that portion of the conveyor belt 37 which curves around thedrive sprocket wheels 36.

In order to better control the removal of vapor-laden atmosphere fromthe chamber 44 and prevent accidental losses of material undergoingdrying from the chamber 44, it is preferable to employ the side walls 92and 92' which are shown best in Figs. 1, 4, 11 and 13 and which will bedescribed more in detail hereinbelow. However, it may be mentioned atthis point that the marginal edges thereof are disposed in contiguousrelation with the inner surface of the loop portion of the endlessconveyor belt means and the outside surface of the drum 31 that iswithin the chamber 44. For promoting the removal of vapor-ladenatmosphere at suitable exhausting fan (not shown) may be connected to anopening such as the port 65 (Figs. 1 and 11) in the wall 92. Theexhausting fan or other suitable exhausting means may be similar toexhausting fan-means 66 shown in Fig. 16 but has been omitted from Figs.1, 2 and 11 in order to simplify the drawings of the embodiment shown inthese figures. While such side wall means preferably are employed, theymay be largely or wholly omitted and in such case convection currentsand atmosphere movements resulting from the operation of apparatus maybe relied upon to remove the vapor-laden atmosphere from the chamber 44without the employment of an exhausting fan and in such case the whollyor partially open sides which permit such currents and movements of theatmosphere are to be regarded herein and in the claims as means forremoving vapor-laden atmosphere from the chamber 44 wherein the wetmaterial to be dried is exposed to drying atmosphere.

The endless conveyor belt is maintained under proper tension at alltimes by a pair of sprocket wheels 47 adjacent the drum 31 that carry orengage the conveyor belt 37 through its endless chain side elements 38.Sprocket wheels 47 are mounted on a shaft 48 (see Fig. 3) carried at itsopposite ends on a frame 49 pivoted to the main frame 30 by a shaft 50and weighted by weights 51 to urge the sprocket wheels 47 upwardly.

The inside surface of that portion of the endless conveyor belt 37 whichsurrounds the heated outside cylindrical peripheral surface 52 ofcylinder or drum 31 is spaced therefrom by structure fully describedhereinafter to provide a wide, thin heating chamber or space 53 in whichmaterial being dried is heated. It is a feature of this invention thatby employing the resiliently acting tensioning means, the thic'kness ofthe layer of material that becomes sandwiched in the space 53 betweenthe outside surface of the drum 31 and the inside surface of the endlessconveyor belt means may be permitted to become increased. Ordinarily theapparatus is intended to operate so as to maintain a predetermineddesired thickness for this layer. However, under certain conditions suchas increase in the amount of feed either accidentally or deliberatelythe thickness of the that because the endless conveyor belt 37approaches generally tangentially the bottom of the heated outsideperipheral surface 52 of drum 31 and because the outside drum surface 52and the inside surface of the conveyor belt 37 travel in the samedirection they cooperate to provide a gradually narrowing or taperingfeed throat '54 (Fig. 3) formed by approaching travelling surfacesthroughout the axial length of the heated surface 52 and through whichmaterial being dried is fed, as hereinafter described, into the wide,thin heating chamber 53.

Damp, wet or pasty material to be dried is fed into the apparatusthrough a primary feeder 55 located on top and at one side of the mainframe 30. Feeder 55 includes a material-receiving hopper 56, the bottomof which is formed by a pair of side by side rolls 57 mounted on spacedparallel shaft means 58 carried in bearings 59 on main frame 30. Thecylindrical peripheral surfaces of the rolls 57 abut each other and oneof the rolls 57 is formed throughout its length to include a smoothcylindrical surface while the peripheral surface of the other roll 57includes throughout its length a plurality of side by sidecircumferential grooves, not shown, whereby material fed or extrudedfrom the hopper 56 between the rolls 57 will be in the form of aplurality of strips or ribbons. ,connected by similar gears 60 (seeFig. 1) so that when The shafts 58 of rolls 57 are interrthe rolls aredriven they will rotate together in opposite directions. The rate ofspeed at which the rolls 57 are rotated, of course, determines the rateat which material 7 is fed into the drier apparatus, and these rolls 57are driven by conventional apparatus by which their rate of a rotationmay be controlled.

The mechanism for driving the rolls 57 as aforesaid may comprise themotor 61 (see Fig. 2), the belts 62 and 63 and some conventional means64 for reducing the motor speed and regulating the speed at which therolls 57 are driven.

Material fed from the hopper 56 by the rolls 57 falls by gravity upon asteeply inclined feed chute or trough 71 and from it directly onto theupper surface of the bottom run 45 of conveyor belt 37 and at the rightside thereof as seen in Fig. 2. Trough 71 is hung loosely at its top endfrom the main frame 3 and because the materials being fed therethroughmay have sticky characteristics, an electrically operated vibrator 72 ofany wellknown construction is mounted upon the bottom of the feed chute71 for vibrating it, thereby to cause the material to feed down thechute 71.

As mentioned previously, the bottom run 45 of conveyor belt 37 travelstoward the drum 31 and approaches the bottom of the latter tangentiallyto form the gradually narrowing or tapering feed throat 54 and thusmaterial dropped upon the insideor top surface of the bottom run 45 ofendless conveyor belt 37 by the feed chute 71 will be conveyed towardthe bottom of the drum 31, through the feed throat 54 and will becomecompressed and confined or sandwiched in the heating chamber 53 betweenthe inside surface of the conveyor belt 37 and the outside heatedperipheral surface 52 of the drum 31. Because the drum 31 and conveyorbelt 37 rotate together as a unit, material confined or sandwiched inthe heating chamber 53 will be carried from the bottom of drum 31 up oneside and over the top thereof and into the top of the aeration chamber44.

As the material enters the top of the aeration chamber 44 it will, forthe most part, be in a compressed sheetlike condition forming a blanketor coating adhering to the outside surface 52 of drum 31, though some ofit may adhere to and travel with the inside surface of the top run 46 ofthe conveyor belt and some small particles of it may fall in theaeration chamber directly onto the bottom run 45 of the conveyor belt37.

A scraper assembly, indicated generally by the reference character 73,for scraping material that adheres to top run 46 of conveyor belt 37extends transversely through the aeration chamber and side walls 92 and92',

and includes a support formed of an inverted angle bar 74 attached atits opposite ends to the center portion of upright lever arms 75. Theupper ends of arms 75 are pivotally attached to the main frame 30 bypivot pins 76. A scraper blade 77 made from a sheet of flexibleresilient material, such as stainless steel, is secured along its bottomedge to one flange of the angle bar 74 and its top edge is urged againstthe inside surface of the top run 46 of the conveyor belt 37 by a pairof springs 78 extending between the lowermost or free ends of the leverarms 75 and the main frame 30. Any material scraped from the insidesurface of the top run 46 of the conveyor belt 37 by the scraper blade'77 will fall by gravity in the aeration chamber 44 directly onto thebottom run 45 of the conveyor belt.

A scraper or doctor blade assembly, indicated generally by the referencecharacter 79, is provided in the aeration chamber 44 for scraping,breaking or digging material from the outside heated cylindrical surface52 of drum 31 and causing it to fall in the aeration chamber 44 directlyonto the bottom run 45 of the conveyor belt 37.

The details of construction of the scraper or doctor blade assembly 79may best be understood by reference to Figs. 3, ll, 12 and 13 of thedrawings. It includes an angle member 86 that extends horizontallythrough the aeration chamber 44 parallel to the axis of rotation of thedrum 31. Angle member 8i includes an integral downwardly extending leg81 at each of its opposite ends which are pivotally attached through apair of axially aligned bolts 82 to brackets 83 bolted to the main frame30. Angle member 80, and consequently the entire doctor blade assembly79, may be adjusted about the axes of bolts 82 by threaded adjustingrods 84that interconnect the top of the angle member and the main frame30. As best seen in Figs. 3 and 10 of the drawings, the angle member 80lies in a horizontal plane below a generally horizontally extendingplane passing through the axis of rotation of shaft 34 and the axis ofrotation of the drum 31, and its flanges extend toward the drum 31, onesloping upwardly toward it, and the other sloping downwardly.

The upwardly sloping flange of angle member 80 carries an upwardlyextending scraper blade 85 formed of a thin resilient sheet of stainlesssteel. Blade 85 extends throughout the axial length of the heatedoutside cylindrical surface 52 of drum 31 and its upper or scraping edgeengages said surface 52 under pressure to scrape, break or dig materialfrom the surface 52 of the drum as the latter rotates against the blade85. Blade 85 is rigidly attached along its bottom edge to the upwardlysloping flange of angle member 80 and the scraping pressure exerted bythe upper scraping edge of said blade 85. on

the surface 52 of the drum 31 is, of course, adjusted or determined byadjusting the position of the scraper or doctor blade assembly 79 aboutthe axis of bolts 82 by the rods 84. The scraping edge of said blade 85is just above the said plane that passes through the axis of rotation ofshaft 34 and the axis of rotation of the cylinder or drum 31 in orderthat the sloping upper surface of blade 85 will deflect, direct, orotherwise cause material which has been scraped from the drum surface52' and is falling toward the bottom run 45 of endless conveyor belt 37to follow a trajectory beginning at the surface 52 and terminating atthe inside or upper surface of the bottom run 45 of said conveyor belt37 in order that the falling material will land upon the latter at apoint more remote from the drum 31 and the mouth of the feed throat 54.

It will, of course, be seen that the material will be broken into piecesupon being cracked, broken or dug from the surface 52 and that thiscracking or breaking of the material will expose more surfaces of ittoaeration as it falls in the aeration chamber 44. It will also be seenthat when the material impacts upon the inside surface of the bottom run45 it may be further broken to prepare it better to be refed to theheating chamber 53 and that there may occur a splashing action when thematerial strikes the bottom run 45 of conveyor 37. This splashing actionhas a tendency to distribute the material more evenly upon the bottomrun 45, thereby aiding in the refeeding of the material through the feedthroat 54 and into the heating chamber 53.

The bottom flange of angle member 80 carries a plurality of hooks 8t;spaced along its length and from which there is hung for swinging motionan angle member 87 (see Figs. 3, 12 and 13). Angle member 87 extendsacross the aeration chamber 44 and has a restriction plate or curtainmeans 88 depending therefrom into the feed throat 54. In the embodimentshown the curtain-88 is formed from a thin resilient or springlike sheetof stainless steel disposed particularly in the region of its lower endcontiguously with respect to the outside material-receiving surface 52of the drum 31 so that when the apparatus is in operation material beingfed through the throat 54 will contact the curtain and in the zone ofthe throat 54 where the curtain is located it will be prevented fromcoming into tractive contact with the outside surface of the drum, as isapparent especially in connection with Figs. 3 and 12.

The bottom of the restriction plate or curtain 88 is notched at 89 (seeFigs. 11 and 13) to provide a succession of restricting elements in theform of side-by-side tongues, fingers or ribbonlike strips 90 betweenwhich the spaces provided by the notches 89 are disposed.

The length of the restriction plate or curtain means 88 is such thatwhen material to be dried is being fed through the feed throat 54 aportion of the material will rest against the curtain rather than thetravelling surface of the drum. As indicated in Figs. 3 and 12 of thedrawings, the length of the curtain preferably is such that the bottomends of the striplike fingers extend into the feed throat 54 so thatwhen the apparatus is not in use they may rest upon the inside surfaceof the bottom run 45 of the conveyor belt 37 in the feed throat 54adjacent the heating chamber 53. However, when the apparatus is in useand material is being conveyed upon the conveyor belt 37 through thefeed throat 54, the material in being compressed within the feed throatwill press against the striplike tongues 9i) and press them into rubbingcontact with the outside travelling surface 52 of the drum 31. However,in the regions of the notches 89 between the striplike fingers 9n thematerial being fed through the feed throat is exposed to tractivecontact with respect to the travelling outside surface 52 of the drum31.

The exact action of the restriction plate or curtain means 88 on thefeed of material to be dried through the feed throat 54 and into theheating chamber 53 has not been fully ascertained, but experience hasshown that the presence of the restriction plate or curtain means verygreatly improves the overa'il action of the drier of this invention.While the action of the restriction plate or curtain means has not asyet been fully ascertained, it is believed, however, that the curtainmeans serves to control and improve the feed of the material through thefeed throat 54 by diminishing the tractive contact of the material to bedried with the travelling converging surfaces at the feed throat whileat the same time permitting such tractive contact with the approachingtravelling surfaces as to effectively draw the material to be dried intoand through the feed throat. This is especially the case in the regionof the striplike fingers for to the extent that portions of the materialto be dried come in contact with these fingers the tractive contact withthe travelling drum surface is diminished. On the other hand, in thosezones or areas between the fingers the material to be dried is exposedto tractive contact with the drum surface so as to effectively draw thematerial into the feed throat without bridging or other damming up ofthe material so as to fail to enter and pass through the feed throatinto the heating chamber 53. While normally not essential, a vibrator(not shown) may be employed so as to minimize any bridging or otherdamming up of material entering the feed throat if there should be anysuch tendency. The fingers 39 may to a certain extent result in thematerial to be dried being somewhat less compressed in the regions ofthe fingers as compared with the compression in the regions of thenotches 89. However, in the final stages of compression any suchinequalities are largely or substantially completely equalized in thefinal formation of the substantially continuous layer as it enters theheating chamber 53. In a typical operation such as the drying of finelydivided coal or sewage the material to be dried may pile up at the feedthroat to a depth of about 5" to 6 and during passage through the feedthroat the layer ultimatelyproduced may be in the neighborhood of to Ain thickness. Under such conditions, which have been mentioned merelyfor purposes of illustration, it has been found desirable to employ acurtain which is about 12" from top to bottom and wherein the fingerlikestrips are at least about 6" or preferably at least about 8 long. Whenthe fingerlike strips are made of stainless steel which, for example,may be 0.007" in thickness, it has been found that very satisfactoryfeeding can be obtained when the strips are about 1 in width and arespaced apart by a distance of about 1. Under such conditions there is anoverall effect of the curtain means on the material passing through thethroat so that a substantially continuous layer is produced. Preferably,the bottom edge of the curtain means does not extend completely to thebase of the throat 54 where the approaching travelling surfaces comeinto closest proximity to each other. For example, it is usuallydesirable to accomplish the last to of reduction in thickness underconditions which expose the material to be dried to the full tractiveeffect of the approaching travelling surfaces.

While an illustrative example has been given of the use of curtain meansfor controlling and improving the feeding of material to be dried, it isto be understood that this has been for illustrative purposes and thatthe restriction plate or curtain means may have different applicationsand different structural embodiments. For example, it may be mentionedthat while the curtain means has been shown as in contiguous relationwith respect to the outside surface of the drum, an analogous effect inreducing the amount of tractive contact of the material passing throughthe feed throat with the converging travelling surfaces may beaccomplished by disposing the curtain means in contiguous relation withthe endless conveyor belt means. Moreover, in certain cases the curtainmeans may be used in contiguous relation with both the outside surfaceof the drum and the inside surface of the endless conveyor belt meanswhere these surfaces converge to provide the feed throat. It also is tobe understood that the curtain means that has been hereinabove describedis merely illustrative of apparatus and utilization-of such curtainmeans for the purpose of controlling and improving the feeding ofmaterials between two surfaces whenever such surfaces travel in the samedirection on approaching orbits so as to form a feed throat within whicha workable material is exposed to tractive contact with the approachingtravelling surfaces.

While an example has been given as regards the construction andproportioning of one type of curtain means, it is to be understood thatboth the construction and the dimensions may be changed substantially,depending on such factors as the action to be achieved, the type ofmaterial being handled by the apparatus and the size of the apparatus asa whole. For use in connection with commercial scale drying operationswherein the material to be dried is a material such as finely dividedcoal, pigment or sewage, it is preferable to employ curtain means havingfinger elements which are at least is possible to utilize other types ofconstruction such as a succession of wires, cords or chains which aredisposed adjacent at least one of the approaching travelling surfaces incontiguous relation therewith. While it is preferable to use asuccession of spaced flexible members which in use drag on the surfaceof at least one of the approaching travelling surfaces, the curtainmeans could be rigidly supported so as to be maintained out of contactwith an approaching travelling surface so long as the curtain means isin closely contiguous relation therewith so that the regions wherematerial being fed into the feed throat is in contact with the curtainmeans are in immediately adjacent relation with regions where thematerial is in tractive contact with the travelling surface. Thestriplike fingers which are used should be such that the material beingdried may readily occupy a the spaces between them for tractive contactwith the travelling surface that is contiguous with the fingers.

In its use it has been found that the curtain means which is .a featureof this invention serves to minimize the occurrence of uneven compactingor wadding of material being formed into a layer at the base of the feedthroat, which uneven compacting or wadding may be very serious in thehandling of certain materials. Moreover, the control on the compactionthat occurs in the feed throat aids very materially in enabling thematerial to travel from one end of the drum to the other under theconditions hereinbelow to be described while the material is beingrepeatedly removed from the drum and being refed through the feed throatso as to again become sandwiched between the outside surface of the.

drum and the inside surface of an endless conveyor belt means.

At the discharge side of the drier apparatus there is a chute or trough91 through which dried material is discharged from the drier (see Figs.1, ll, 12 and 13).

Discharge chute 91 is mounted at its upper end on an upstanding wall 92that extends longitudinally of the conveyor belt 37 and at the sidethereof. A seal means 93 is attached to the bottom edge of the wall 92and is preferably composed of either a single strip of thin resilientsheet material or a plurality of abutting shorter lengths of such sheetmaterial, e.g., a thin flexible sheet of stainless steel, the lowermostedge of which is resiliently maintained in pressure contact with theupper surface of the bottom run 45 of the endless conveyor belt means37. A similar wall 92 (see particularly Fig.

11) and seal means 93 are provided at the opposite or feed side of thebottom run 45 of the endless conveyor belt means 37. It is desirablethat the walls 92 and 92' and the seals 92' and 93, particularly thelatter, be extended as far as possible into the feed throat 54 so as tocooperate with the seal means hereinafter described that is providedbetween the periphery of the drum 31 and inner surfaces of the conveyorbelt means 37 for preventing any loss of material that has been fed intothe chamber over the edges of the endless belt conveyor means and sothat when the material is compressed and compacted in passing throughthe feed throat 54 and in becoming sandwiched between the drum surface52 and the inside surface the endless conveyor belt means will spread inone direction and be caused to travel in movements from the feed side tothe discharge side of the chamber 44 as the material is repeatedlyremoved from the drum and refed therein during the drying operation.

As more clearly shown in Fig. 11 seal means 67 is provided at the top ofthe 'wall 92 and is resiliently maintained in pressure contact with theunder surface of the upper rim 46 of the endless conveyor means 37. Theseal means 67 is similarly provided along the upper edge of the sidewall 92. Preferably the side walls 92 and 92' have the inwardly slopingportions 68 and 68' respectively.

The ends of the walls 92 and 92' that are adjacent the drum 31 areshaped so as to be contiguous therewith and the opposite ends of thewalls are shaped so as to be contiguous with the inner surface of thecurved extremity of the'loop portion of the endless conveyor belt meansas it passes around the sprocket wheels in supported relation therewith.The side walls 92 and 92' may be supported from frame 30 in any suitableway, e.g., by the employment of brackets 69 and 69 as illustrated inFig. 11.

It is apparent from the foregoing that an enclosed drying chamber isprovided which, except for the side walls 92 and 92', is formed by themoving functional parts of the apparatus. Where portions of theapparatus pass through the side walls, as, for example, the feed chute71, the discharge chute 91 and the angle 80, appropriate I openings areprovided and incoming dryingatmosphere may enter through these openingsto compensate for vapor-laden atmosphere exhausted through the openingin the side wall 92. Moreover, as mentioned above it is not essential tooperability that the side walls 92 and 92 extend to the top of thechamber 44 but it is important that suitable side wall means he providedalong the upper surface of the lower run of the endless con-,

- veyor belt means particularly in the region of the feed throat 54.

Discharge chute 91 slopes downwardly from its upper edge, which islocated within aeration chamber 44, to the outside of the main frame andchamber 44 and it rests adjacent its bottom against main frame 30 asindicated in Fig. 13 of the drawings. At its top or material-receivingend discharge chute 91 carries a control element in the form of a shorttrough 94 pivoted on a horizontal axis at its bottom by a hinge to thetop edge of the bottom of chute 91 so that dried material received orcaught by it will flow into the chute 91 to be discharged from thedrier. Trough 94 is positioned below the bottoms of the angle membersand 87 and in the trajectory of material falling from the heated outsidecylindrical surface 52 of drum 31 whereby it will catch some of saidfalling material. Trough 94 may be adjusted about the axis of itsmounting hinge by an adjusting rod 95 thereby to adjust the depth towhich the top edge of its bottom drawings.

extends laterally into said falling material and consequently to adjustthe amount of material removed from the drier apparatus upon eachrevolution of the drum 31.

The endless conveyor belt 37 includes two spaced endless chains 38disposed along and forming the marginal edges thereof. One of thesechains 38 is shown in detail in Figs. 5, 6 and 7 of the drawings. Eachchain 38 is built up of a plurality of yoke shaped links 96 including aknuckle barrel 97 and two side arms 93 that extend therefrom and overlapthe ends of the knuckle barrel 97 of the next adjacent link 96. Thelinks are pivotally interconnected by knuckle pins 99 that extendthrough the ends of the arms 98 of one link and pivot in the knucklebarrel 97 of another. One arm 98 of each link 96 includes an ear or lug100 to which a flange 101 of an angle member 102 that extendstransversely of the conveyor belt 37 and between the spaced chains 38 isbolted. The other flange 103 of the angle member 102 extends at a rightangle to flange 101 and is notched adjacent each of its ends as at 104to clear the ends of the adjacent knuckle pins 99.

As indicated in Fig 6 of the drawings, the flanges 1 of the adjacentangle members 102 all lie at the inside of the endless conveyor belt 37and adjacent the heated surface 52 of drum 31 and they provide a backingsurface for a plurality of overlapping imperforate sheets or linerplates 105 which is flexible only at right angles to the direction oftravel of the conveyor belt to permit it to pass concentrically aroundthe drum 3'1 and the sprocket wheels or pulleys 36 and 47.

upright side edges of the notches 104 in the flanges 103 of anglemembers 102, as clearly shown in Fig. 7 of the The leading end 106 ofeach of the liner sheets or plates is bent at a right angle and extendsbetween two adjacent angle members 102 and is attached as by rivets 107to the flange 103. The trailing end or edge 108 of each liner sheet orplate overlaps the leading edge of the next or following liner sheet orplate 105, as indicated in Fig. 6 of the drawings, and the marginalportion of this trailing end may be bent toward the inside surface ofthe next or following liner sheet or plate in order that when the sheetor plate 105 is forced toward the flanges 1.01 the trailing edge of theliner sheet or plate 105 will be held resiliently in sealing relationwith the next liner sheet or plate.

The chains 38 of conveyor belt 37 engage and rotate with peripheral rims109 one of which is adjacent each I end of the drum 31, and the ends ofthe drum 31 at the sides of the heating chamber 53 adjacent said rims109 are sealed to the inside surface of the endless conveyor 37 formedby the liner sheets or plates 105 to prevent material from working orbeing worked from said chamber 53 at the ends of the drum 31.

The rims 109 are each formed of a plurality of segments (see Fig. 10)bolted onto the end of drum 31 to provide the complete circular rim 109.As best seen in Figs. 7 and 9 of the drawings, each segment of the rim109 includes a band or tire element 110 and an end element 1 11 thatforms a radially inwardly extending flange through which the segment maybe bolted to one side of a cylindrical band 112 that surrounds theoutside or heated cylindrical peripheral surface 52 of the drum 31 andis welded to the latter. It will be seen from Fig. 7 of the drawingsthat the thickness of the band 112 and/ or tire 110 may be changed toadjust the distance between the heated surface 52 of drum 31 and theinside surface of conveyor belt 37 and, consequently, the thickness ofthe heating chamber 53.

Each rim 109 carries a plurality of overlapping rec tangular leafsprings 113 that cooperate to form a resilient compressible ring thatsurrounds the end of the drum and is compressed by the inside surface ofthe liner sheets or plates of the endless conveyor 37 as the lattertravels concentrically around the drum 31. Each leaf spring 113 is madeof a thin rectangular sheet of stainless steel and they are arranged inside-by-side overlapping or shingle-like relation, as indicated in Figs.5, 6 and 10 of the drawings. These springs 113 extend between the bandor tire and the band 112 and are riveted to the inside surface of theband or tire 110, as clearly seen in Fig. 9 of the drawings. The freeends of leaf springs 113, as indicated in Fig. 7 of the drawings, arebent or curved radially outwardly of the drum 31 and bear against theinside surface of the liner sheets or plates 105 of conveyor belt 3 7 assaid conveyor belt is carried around the drum. The leaf springs 113instead of being made of stainless steel may be made of pieces of someother flexible resilient sheet material, and it has been found that suchpieces when attached to one arcuate member in side-by-side overlappingrelation so that their extremities are maintained in resilient contactwith an adjoining arcuate member an effective sealing means is providedbetween such members. Preferably such resilient contact is provided bycausing the pieces to be normally curved and causing pressure contactwith the extremities of the pieces to deform them from their normalcurvature, as by causing them to be straightened out in the case of theembodiment shown.

In order to remove material which might become packed between the leafsprings 113 and the peripheral surface of the cylindrical band 112 thereis provided within the aeration chamber 44 a pair of scraper fingers114, one for the seal at each end of the drum. These scraper fingers 114(see Figs. 11, 12 and 13) extend upwardly from and are carried by theangle member 80 of the doctor blade assembly 79. The upper end of eachfinger 11 4- includes two scraping edges 115 and 116. Scraping edge 115scrapes material from the heated surface 52 of the drum adjacent theband 112 and scraping edge 116' projects under the leaf springs 11.3 andscrapes material from the peripheral surface of said band 112. Eachfinger 114 also includes a cam surface 117 over which the leaf springs113 pass. This cam surface 117 functions to scrape material from. theinside surfaces of the springs 113 and it also tends to maintain saidsprings properly shaped since the springs 113 are deflected radiallyoutwardly as they pass over the cams 117. It will be seen that materialremoved from the drum assembly 31 by the scraper fingers 114 will falldirectly onto the bottom run 45 of conveyor belt 37.

It may be pointed out here that when the drier apparatus is to be usedto dry certain chemicals and foodstuffs it is desirable that thesurfaces of the parts of the drier that come in direct contact with thematerial, such, for example, as the feed chute 71, the inside of theconveyor belt 37, the cylindrical member of the drum assembly 31 thatforms the heated surface 52, the scraper blades 77 and 85, the dischargechute 91, etc., be made of a material which will not react with orcontaminate the material being dried, or itself be detrimentally actedupon by the material. It has been found that stainless steel is one suchmaterial, and although other materials may be used for the purpose, orthe parts may be plated with other materials, all of said elements inthe machines herein described are made of stainless steel.

It-may also be pointed out here that since the liner sheets or plates105 of the endlms conveyor belt 37 are attached to the transverse anglemembers 102 thereof only at their leading edges it is desirable tosupport them as they travel along the top run 46 of the chain loopbetween the drum 31 and the sprockets 36 and to shape them as theytravel around the sprockets 36. For this purpose a plurality of curvedbars 118 having straight upper leg portions 119 are mounted to the mainframe 30 with their top leg portion 119 extending from between thesprockets 36 toward the drum 31 (see Fig. 3).

Suitable hold-down arms 120 are provided for hold- 15 ing and shapingthe liner sheets or'plates 105 to*cause them to follow the curvature ofthe conveyor belt 37 where it passes over the tensioning sprockets 47;These arms 120 are each mounted for vertical swinging or pivotal motionabout a horizontal axis extending transversely in the aeration chamber44 by a plurality of axially aligned pivot pins 121 in brackets on anangle member 122 which is supported by members 196 in verticallyadjustable relation thereto as by nuts 197 carried by bolts that passthrough vertical slots 198 in the member 1% (Figs. 1 and Each arm 120 isurged by a spring 123 to rotate in a clockwise direction, as seen inFig. 3 of the drawings, and the free end of each am 120 extends into thefeed throat 54 and is properly curved to hold and guide the liner sheetsor plates 105 as they pass thereunder. These arms 120 are provided forthe sole purpose of causing the liner sheets or plates 105 to flex andfollow the path of the chains 38. They in no way aid in feeding materialeither through the feed throat 54 or axially of the drum 31 and may evenbe omitted in certain embodiments of the invention (see Fig. 16) whereinthe tensioning sprockets 47 engage the bottom run 45 of the conveyorbelt 37 where the latter becomes'tangent V to the bottom of the drum 31.

. upon the travelling bottom run 45 of the endless conveyor belt 37adjacent one edge thereof and is conveyed by the conveyor belt 37through the feed throat 54 and under the restriction plate or curtainmeans 88. After a being compressed in said feed throat 54 the materialis fed or sandwiched into the heating chamber 53 and carried therein,while being heated by the heated surface 52 of the drum 31, from thebottom of the drum up or around one side-of the latter and into the topof the aeration chamber 44. The material will, of course, be quite hotwhen it enters the top of the aeration chamber 44 and immediately uponpassing from the heating chamber 53 it will be exposed to air in theaeration chamber and will begin to give up to it some of its fluidcontent. It will be apparent that, as previously described, most of thematerial after leaving the heating chamber will adhere in the form of ablanket to the heated surface 52 of the drum and will travel with itsubstantially through .a quadrant or 90 arc of travel until saidmaterial is scraped therefrom by the doctor blade 85. While said:material is adhering to and travelling with said heated :surface 52throughout said quadrant it is, of course, still Ibeing heated, with theresult that some of its fluid constituent, generally water, may bedriven by said further Fheating from the material and into the air inthe aeration chamber 44.

The doctor blade 85, as previously described, scrapes, :breaks or digsthe material from the outside heated surface 52 and in so doingdisintegrates the material, thereby exposing more surface or surfacesthereof through which the material may give up its moisture to the airin the aeration chamber 44. The material may be further disintegrated inthe aeration chamber 44 when it strikes the bottom run 45 of theconveyor belt 37. It will be seen that the effect, which may be comparedto a splashing effect, on the material upon striking or impacting uponthe bottom run 45 of conveyor belt 37 will tend to cause the material tobecome more evenly distributed upon the conveyor. Likewise when thematerial is forced through the feed throat a very substantial crushingaction takes place so as to disintegrate lumps that may be present inthe material to be dried either when it is fed into the apparatusorastheresult of caking on drum surfac e during those intervals when itis in the drying chamber 53 between the drum surface and the endlessconveyor belt means. Some materials, such, for example, as certainpigments, tend to become caked into lumps that, if not broken up, arerelatively difiicult to dry because of the extent of the travel ofliquid to be removed from the interior to the exterior of the lumps.However, by intially breaking up such lumps and likewise breaking up andcrushing any lumps formed during the drying operation, the rate anduniformity of the drying is greatly improved. 7

The above described travel of material by the conveyor belt 37 from theaeration chamber 44, around the drum 31 in the heating chamber 53 andreplacement of the material upon the conveyor belt 37 is repeatednumerous times by the same material as it works or is worked axiallyalong the drum in the heating chamber53 from the feed side to thedischarge side thereof; The number of times any given quantity ofmaterial rotates around said drum 31 and hence also the rate of lateraltravel may be controlled by controlling the amount of .material removedfrom the apparatus at the discharge end of the drum 31. This may bedetermined by adjusting the receiving portion 94 of the discharge troughto catch more or less of the material scraped from the drum 31 as itfalls in the aeration chamber 44. be seen that the rate of feed ofmaterial through the apparatus may be controlled merely by balancing therates of feed of material into and out of the machine by adjusting thespeed of operation of the primary feeder 55 and the position of thedischarge trough 94, and thus the material being fed through the machinemay beretained therein and subjected to drying action for variousperiods of time, as may be necessary, to dehydrate or dry it to anydesired percent of fluid content.

It has been found that the lateral travel of the material to be driedmay be effected and controlled in a very desirable manner as has beenreferred to hereinabove. During drying the removal of fluid such aswater results in change in the physical characteristics of the material.One of these changes that frequently occurs is overall shrinkage of thematerial and this presents certain prob lems in keeping the content ofthe space between the drum and the endless conveyor belt means full andunder desired conditions of compactness throughout the lateral extent ofthe drum. By feeding the material to be dried adjacent one end of thedrum at which a seal is maintained between it and the inner surface ofthe endless conveyor means as the material is sandwiched therebetween agradual movementof the material occurs from adjacent the feed end of thedrum to adjacentthe discharge end as the'material is repeatedly fed soas to. be carried on the surface of the drum, removed and refed thereon.Moreover, notwithstanding changes in the physical characteristics of thematerial while being dried, the drying chamber 53 remains full and inlike condition of compaction along the lateral extent of the drum for itis the material itself which in being compacted under lateral pressuredifferential conditions that pushes other portions of the material aheadof it, thus preventing the possible formation of zones of low pressureor even voids. Moreover, the presence of the curtain means greatlyassists in maintaining the desired conditions by' reducing somewhat theextent to which the material is' compacted in being reduced to thethickness of the chamber 53 and thereby retaining greater workability sothat the lateral migration is more effectively obtained However,movement laterally of the drum also will occur but in a less desirablemanner even if the curtain means isomitted.

In Figs. 14 and 15 there is shown a modified form of feeder mechanismwhich may be employed in thelembodiment of the apparatus shown in Figs.1, 2,. 3 and.4 or that of Figs. 16, 17 and 18 of the drawings. ,In thismechanism a restriction plate. or curtain means 188 similar to It willthus cin'tainirneansfi sis hungor suspended from its upper end on aplurality of chains 124 attached to a rod- 125 that extends transverselythrough the aeration chamber 44 and which is mounted for rotation at itsopposite ends in bearing blocks 126 attached .to the legs 81 of thedoctor blade assembly 79. Rod 125 may be rotated by a crank 127 to raiseand lower the curtain means 188 and the rod is provided with a ratchetwheel 128 that is engaged by a dog 129 on one of the brackets "83. Itwill be seen that by rotating the rod 125 the depth to which the bottomends of the fingersior strips 190 extend into the feed throat 54 may beadjusted and that such adjustment of the curtain means 188 will alsoadjust. the action thereof in the feed throat 54 as well as the feedrate.

Figs. 16, 17 and 18 showa modification of the machine shown in precedingfigures of the drawings, in which the aeration space corresponding tothe aeration chamber or space 44 is enclosed by an upright wall orconfining partition 129 extending transversely ofthe main frame 30 andbetweenzthe upper and Flower runs 46 and 45, respectively, of theendless conveyor belt 37 and with the upper and lower edges thereof,respectively, contiguous therewith. The aeration space between. the wall129 and the heated surface .52 of drum 31 is divided by an uprightdividing partition 130 into two sideby-side aeration chambers 132 and133 and the outermost ends of these chambers 132 and 133 are closed byidentical upright walls 134 provided with wiper or seal strips 135 thatengage the inner surface of the' bottom run 45 of the endless conveyorbelt 37. Dry air may be introduced into each of the aeration chambers132 and 133' through ducts or conduits 136 and air containing fluidremoved from material being aerated in the chambers may be removed fromthe latter through ducts or conduits 137, each of which may be connectedwith an exhausting device 66 which may, for example, comprise anexhausting fan. Embodiments of this in vention comprising a dividingpartition such as the partition 130 are preferred due to the fact thatby causing the material to be disposed in a different separated zoneduring the final stages of drying when dusting tends to occur, thedust-laden drying atmosphere from which it 'may be desirable to removedust by means of a dust collector may be cut down, e.g., to only about2% or 3% of the total drying atmosphere used to carry away vapor beingseparated from the material during drying.

In the embodiment shown in Figs. l6, l7 and 18 the lower end of theprimary feed chute 71., which may be in the form of a duct, not shown,is extended through an opening 138 in the wall 134 at the feed side ofthe machine .and the discharge chute '91, .94 may extend from theaeration chamber 133 through a similar opening in the other end wall134. It will be noted that in this embodiment of the apparatus thesprockets 147 corresponding generally to sprockets 47 do not function toadjust the tension of the endless belt conveyor but are located directlyunder the drum 31 and support the endless conveyor 37 immediately belowthe point where it feeds onto and is tangent with the drum 31. Thesprockets 147 are placed in this location to assist in holding theconveyor belt 37 tangent to the drum 31 at the discharge end of the feedthroat to and it in compressing material both in the feed throat andwhere it enters the heating chamber 53. To resiliently :maintain theendless conveyor belt means under tension the bearing 35 for the axle 36is spring loaded by resilient "means such as the spring means 199. ldhen sprockets 147 are in the position shown in Fig. 14 it is notnecessary to employ holddown arms adjacent the feed throat such as thearms 12] shown in Fig. 3.

In Figs. '19, 20 and 21 there is shown a modified form of heating 131and mechanisms associated with it that may be substituted for the drum31 in the embodiment of the machine shown in Figs. 1, 2 and 3 or inFigs.- 14, 15 and 16 of the drawings. In this modified structure thedrum 131 is formed of two cylindrical tubes 139 and 140, one within theother and mounted to rotate concen' trically about the axis of a centralshaft 141. The inner tube 1391is of greater length than the outer tubeand projects axially at its ends beyond the end of the outer tube 140.The cylindrical space, steam or hot water chamber 142, provided betweenthe inside surface of the outer cylinder or tube 140 and the outsidesurface of the inner cylinder or tube 139 is closed at the ends of theoutside cylinder 140 by a pair of identical rings 143 welded to bothcylinders 139 and 14%. The outside cylinder 141i is provided at each ofits ends with structure identical to that shown in Figs. 5, 6, 7 and 8of the drawings for re ceiving the chains 38 of the endless conveyor 37and for sealing the ends of the heating chamber 53 provided between thecircumferential surface of the outer heated peripheral surface 52 of theouter cylinder or tube 141) and the inside surface of the endlessconveyor belt 37.

The cylinders or tubes 139 and 140 are carried as an assembly upon acentral shaft 141 by a plurality of tubular conduits in theform ofspokes 144 which connect the steam chamber 142 with the hollow ends ofthe shaft 141. It will be seen that steam, or hot water, introduced intoone end of shaft 141 will flow through the spokes 144 connectedtherewith into and through the steam or hot water chamber 142 to thespokes at the opposite endof the inner cylinder 132 and through theselatter spokes to be exhausted from the drum 131 at the opposite end ofthe shaft 141.

Within the cylinder 139 there is another cylinder 172 that is carried bythe spokes 144 which is separated from the cylinder 139 so as to leavean air space which provides a certain amount of insulation whereby theinner surface of the cylinder 172 will be maintained at a lowertemperature than would be the case if the inner surface of the drum wereto be provided by the inner surface of the cylinder 139. If a greatertemperature differential is desired a heat insulation material could beplaced between the cylinders 139 and 172. It also would be possible toeffect other control as by connecting the space between the cylinders139 and 172 so as to pass therethrough some fluid for controlling thetemperature of the inner surface of the cylinder 172. Alternatively, thecylinder 172 may be omitted. In any case, it is apparent that thestructure of the apparatus may be such that the inner surface of thedrum may be maintained at whatever temperature may be desired.

In the embodiment shown in Figs. 19, 20 and 21, the doctor blade 85which is located as shown in the preced ing figures is terminated sothat for discharge of material from the apparatus a second doctor bladesection 173 is used which causes material that is scraped off thereby tobe discharged onto the inclined screen 174 which is such that any lumpsof substantial size do not fall therethrough but are returned to theendless conveyor belt means to be refed into and through. the throat 54wherein the lumps are crushed and disintegrated. The liner material, onthe other hand, passes through the screen 174 and is caught by the chuteor slide which conveys the partially dried material to the .inside ofcylinder 172 which is preferably provided with a smooth or even polishedinner surface so that the partially dried material will tend to slide onthe surface without subs'tautial tumbling or agitation. In order tominimize any tumbling of the partially dried material the spokes 144 arepreferably streamlined so as to present the narrow edges as shown inFig. 21. During operation and continued rotation of the drum thematerial fed into the inside of cylinder 172 while sliding on the innersurface will gradually work itself to the other end of the cylinderwhere it may be discharged as onto the discharge chute 146. To assist inthe travel to the discharge end of the inner cylinder 172, the verticaldisposition of the surface over which the material flows in beingdischarged is somewhat lower than the level of the upper edge of theannular wall 205 or other confining means at the feed end of cylinder172. Such differential in level may be accom-

